Effects induced by 𝛄-irradiation on intraband transitions in Sr²⁺-doped ammonium zinc chloride crystals

Abstract

Considerable changes were observed in the X-ray diffraction pattern of ammonium zinc chloride after doping with Sr²⁺ in different concentrations and after irradiating with γ rays at different doses. The effect of γ-radiation and Sr²⁺ content on optical parameters of (NH₄)₂ZnCl₄: x Sr²⁺ single crystals (x = 0.00, 0.020, 0.039, 0.087 or 0.144 wt.%) has been investigated. The transmittance near the absorption edge of unirradiated crystals and crystals irradiated with different γ-doses has been measured, hence the absorption coefficient (α) was calculated. The values of α at room temperature increased under the influence of γ-irradiation. The rate by which α increases with photon energy just before the absorption edge is strongly inhibited by higher γ-doses. The type of intraband transition in (NH₄)₂ZnCl₄: x Sr²⁺ single crystals was found to be of the allowed indirect transition, and γ-irradiation had no effect on the type of transition. The values of the optical energy gap (E _g ) were calculated as a function of γ-dose. The effect of γ-irradiation was found to be more pronounced on samples doped with x = 0.087 or 0.144 wt.% Sr²⁺. The results can be discussed on the basis of γ-irradiation-induced defects and Sr²⁺ concentration. A diagram representing probable transitions to the created bands due to irradiation could be constructed.

^*On leave of absence from Physics Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt

Keywords:

• Ferroelectrics
• (NH4)2ZnCl4 crystals
• Optical properties
• γ-irradiation

Acknowledgement

The authors are thankful to the staff of the Radiotherapy and Nuclear Medicine Department, Assiut University for irradiating the samples.

Notes

^*On leave of absence from Physics Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt